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RF limitations on M9 for close focus on WATE


wlaidlaw

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I am trying to make a lens correction profile for the WATE with Adobe Lens Profile Creator for Photoshop CS5. Firstly I needed to ascertain the size of the chequered B&W chart I need to print from the range of supplied test charts. It is very large. Even at close focus for the 16mm, the chart needs to be 30" x 45" - not cheap to get printed!

 

While I was doing this exercise, I checked the RF image coincidence at 0.5m and I noticed it was a long way out - see table below. The error gradually decreased until there was zero error at 1 meter. Is this normal behaviour for the M9 with a WATE and is just going beyond the reasonable limitations of the rangefinder? I presume for close focus distances, I should just use scale focusing. I wish Leica put a little line on the top plate, where the focus plane is, like Contax used to do. I am guessing it is about 2/3 the way to the rear of the body. I suppose I could measure 27.8mm from the front of the mount and mark the top plate with a felt tip.

 

Wilson

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Exactly. It seems the roller arm stop of your M9 is at 67 cm. I doubt that setting has to be very precise. 74 cm for 70 setting seems to be in the ball park to me, given that there is no film plane indication and that the lens sems to be spot on at 100 cm..

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That would explain why the scale settings on the WATE are greyed out below 0.7M. To get the chart as small as possible, I want to use 0.5M but I am concerned that the distortion/vignetting of the WATE at that focus distance will be unrepresentative of the distortion and vignetting at more normal focus distances. However I am not going to make a 2 meter by 3 meter chart to do the profile.

 

Wilson

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Are you going to do this for distortion and vignetting, Wilson? I thought the WATE was quite good in that department.

 

Jaap,

 

Distortion is minimal, vignetting is pretty bad at 16mm on the M9. Never noticed it with the crop factor on the M8 but you can see it in nearly every shot with the M9. If it is an easy correct on CS5, I might as well get the benefit of my expensive upgrade.

 

Wilson

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Guest trond

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Dear Wilson,

 

I agree with Jaapv in this respect; I have used two different copies of the WATE, and have found the vignetting on M9 to be minimal.

 

If you have a lot of vignetting, you should get the lens checked, as the vignetting on the M9 should be almost non existing even at full aperture.

 

Best regards

 

Trond

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Dear Wilson,

 

I agree with Jaapv in this respect; I have used two different copies of the WATE, and have found the vignetting on M9 to be minimal.

 

If you have a lot of vignetting, you should get the lens checked, as the vignetting on the M9 should be almost non existing even at full aperture.

 

Best regards

 

Trond

 

Trond,

 

Take a picture of a white wall in brightish light. You may be shocked by the amount of vignetting. Now I know the asymmetry of the vignetting varies from M9 to M9 and mine is probably in the less good 50%. I noticed the problem first when I was taking pictures in the snow. This was prior to the FW update so the vignetting was pink into the bargain. The FW update has almost cured the pink but the vignetting seems worse if anything and I am hoping the lens profiling can cope with asymmetric vignetting. I don't think there is anything wrong with the lens, it may be my M9 if anything. However as everything else is working well, I don't want to tempt fate and get a technician fiddling with it. he might cure the vignetting and make something more important worse.

 

Wilson

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i use the wate a lot and it seems quite a sensitive lens, i think because mine somehow went out of alignment. suddenly it started to flare on one side and distort verticals horribly beyond correction. it may have been a small, unnoticed ding that did it but anyway it's away being adjusted. could this be the reason you see that "vignetting varies from m9 to m9"? could it be that your wate and not your m9 is somehow out of adjustment?

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